Question: which star is companion of Alpha Centauri B and have least proper motion?
Paraphrase: Of Alpha Centauri B, what star has the least proper motion and is also a companion?
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q523 . ?ent wdt:P2215 ?obj . ?ent wdt:P399 wd:Q1052548} ORDER BY ASC(?obj)LIMIT 5 
Answer: Alpha Centauri A, Alpha Centauri A